Every caller of svc_take_page ignores its return value and assumes it
succeeded.  So just WARN() instead of returning an ignored error.  This would
have saved some time debugging a recent nfsd4 problem.

If there are still failure cases here, then the result is probably that we
overwrite an earlier part of the reply while xdr-encoding.

While the corrupted reply is a nasty bug, it would be worse to panic here and
create the possibility of a remote DOS; hence WARN() instead of BUG().
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NNeil Brown <neilb@suse.de>
Cc: Ingo Oeser <ioe-lkml@rameria.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>